Program transmission over wires



July 6 1926.

' 1,591,108 J. F. TOOMEY PROGRAM TRANSMISSION OVER WIRES Filed Nov. 11,1922 magma.

' INVENTOR. I

BY J1] 230mg m ORNE Y Patented July 6, 1926."

UNITED STATES PATENT OFFICE.

:rorm r. TOOMEY, or NEW YORK, N. 2., assienoa 'roamnarcan TELEPHONE AND.v

TELEG A H COMPANY, A CORPORATION or new YORK.

lPROjIiIEtAlVlI TRANSMISSION OVER WIRES.

Application filed November 11, 1922. Serial No. 600,357..

This method, however, has very seriousobjections. In the first place,numerous broadcasting stations in the same area operate on wave lengthssufficiently close together to interfere with each other. Furthermore,radio telephonic transmission'necessarily' involves the use of a. muchwider band of the frequenc spectrum than is used for wireless telegrappurposes, and in .view

of the fact that the number of wave lengths available for radiocommunication are necessarily limited it is undesirable that wavelengths necessary for commercial communication should be utilized forvurposes of 0 mere entertainment. Finally, in order to avail himself ofthe distributed information or entertainment, each individual subscribermust provide himself with .a radio receiving equipment which involvesstoring upon his are constantly in need of re-charging, together with aconsiderable. amount of dell.-

cate and elaborate electrical apparatus, such as coils, detectors,amplifiers, etc., all of which involve careful maintenance. Moreover,the radio receiving set as now known is, at its best, an inherently uglything, absolutely out of place in the home and re: quiring for itsoperation a network of unsli htly wiring.

fiealizingthe inherent limitations of radio broadcasting, roposals havebeen made to use existing wire systems, such as telephone,- telegraph orpower networks for program transmission purposes by transmitting carrierfrequencies over such existing power or communication lines. Such amethod, however, would .be extremely expensive as .well ascomplicated,,as it involves 'a very considerable reorganization of thetelephone premises expensive storage batteries whichv plant or powerplant, and requires the use of quite comphcated and expensive apparatus.

The ordinary telephone plant, however, ofl'ers unusual facilitiesforprogram transmission purposes by'the use of ordinary telephonicmethodsand without the employ ment of any highfrequency' or carrier metods of signaling. When it is realized that the average subscriberstelephone set is in use for telephonic purposes only during an extremelysmall part of the time it becomes at once apparent that if the telephoneline, during its idle periods, could be used for transmitting'news,information or entertainment, the plant could be used much moreeconomically andthe information or the like distributed could betransmitted to the subscriber'in the simplest manner pos-- sible. It mayfurther be observed that the average subscribe-r to a program service,particularly a service for transmitting entertainment, would only desireto avail himself of the service during the late afternoon or during theevening,'at which times the average subscribers telephone is only usedfor soclal purposes and is rarely or never used for business calls.

llaving these circumstances in mind, it is proposed by this invention toprovide simple, practical and economical arrangements by which news,information, music or other forms of entertainment may be I transmittedat ordinary telephonic frequencies from a central program station oversubscribers telephone lines. It is also proposed by this invention toprovide a system whereby the telephone subscriber may recelve theprogram service without interfering in any way with the use of his linefor .ordinary telephone purposes.

tion'also renders available a program distributingssystem in which theapparatus,

This invennot only at the central station but more articularly at thesubscribers station, wi be extremely simple and economical and yeteflicient. 1

The invention may now be more fully understood by reference to thefollowing detailed description thereof when read in connect on with theaccompanying drawing, in which Figure 1 is a circuit arrangementillustrating-one embodiment of the invention and Fig. 2 is a circuitarrangement illustrating a :similar embodiment provided with anamplifying device for the loud speaker at the receiving station.

Referring to Fig. 1, L designates an ordinary subscribers line to whichprogram service is normally connected through the back contacts of acut-off relay COR. The equipment associated with the subscribers line atthe switchboard, such as the answering jack J and the multiple jacks J,J, etc., is normally disconnected from the line at the contacts of thecut-off relay, this arrangement of the circuitoperating to eliminate thecross-talk interference which might occur between adjacent circuits inthe switchboard cable. A line relay LR is pro; vided, this line relaybeing associated With the portion of the circuit extending from the lineL to the program station instead of being associated with the part ofthe cirout extending to the answering jack. The cut-off relay COR isarranged to be operated over the sleeve circuit of the answering jackwhenever the plug of a cord circuit is inserted in said jack. Thecut-ofi' relay, when actuated, disconnects the program equipment andhence the line relay LR from the line so that it will be apparent .thatincoming calls' to the subscriber may be completed in the usual manner.

The program equipment comprises a trunk T, leading to a program station(not shown). An amplifier 25 is associated with the trunk T throughpatching jacks J for amplifying the program currents to the desiredamplitude for transmission over the lines of the group to which the lineL belongs. In this connection, it will'be noted that subscribers lineshaving similar impedance characteristics may be grouped together andassociated by means of jacks,

such as the jack J to common bus-bars connected to the output of anamplifier, such as 25. The amplifier may be so adjusted as to amplifythe currents to the desired value for all of the lines of the group. Forexample, lines in the same cable having approximately tne same length,the same .gauge conductors and approximately the same capacity, wouldall be grouped on certain bus-bars. The amplifier, such as 25 at thecentral office, associated with this group of lines, would beequippedwith the proper type of output coils and other apparatus so thatit would work at its maximum efficiency when connected to its associatedgroup of lines. Means may alsobe provided when necessary 'for equalizinthe transmission over the various groups 0 subscribers lines.

The arrangement illustrated is designed on the assumption that a fixedprogram will be given at certain hours and consequently a key K isprovided for switching the program station into connection with thebusbars associated with a group of subscribers lines. This key with beactuated during such periods as programs are being rendered. At otherperiods, the key will be in its normal position and its contacts are soarranged that when the key is normal, the

'winding on the cut-off relay COR to indicate to the operator that theprogram serviceis being applied to the line.

The jack J is provided for the purpose of disconnecting any given line,such as L, from its normal group and patching it into connection withsome other program circuit or group. For this purpose the patching cordmay be connected to a multiple (not shown) of the jack J of the otherprogram circuit. The patching jacks J and J 3 are provided for patchingin different amplifiers or for connecting the bus-bars 26 with diiferentprogram stations. By this arrangement a program of one character may beconnected to one group of lines and a program of difl'erent character toanother group of lines. The jacks, however, enable the programs to beswitched from group to group, as the exigencies of the service mayrequire. .The jack J on the other hand, permits the connection of asubscriber, normally ina given group receiving a certain program, to thebus-bars of another group receiving a different program which fie may atthat particular time prefer to ear.

The apparatus at the subscribers station A is extremely. simple,consisting merely of .the standard substation set 10 and a loud lineduring a given period whether the sub;-

scriber desires it or not. If the subscriber does not care to hear theprogram he will simply maintain the contact of the key K open and if hedoes desire to hear the program he may do so by closing the contact ofthe key.' During the rendition of the program, a busy tone'is appliedover the upper contact of the key K at the central oflice, over thelower back contact of the cut-off relay and through the lower winding ofthe cut-off relay to the ground. The

inductive action between the two windings of the cut-off relay transmitsa busy tone to 1the sleeve conductor of the answering Jac If a callshould come in for the line L while the program is being rendered,theoperator may disregard the busy tone and insert the plug P of theusual connecting cord into the answering jack J, or one of the multiplesthereof, thereby energizing the cut-off relay through its upper winding.

' The cut-off relay at once disconnects the line L from the circuitincluding the line relay LR, transformer 27, jack J leads 28, key K,amplifier 25 and trunk T leading to the program station. The subscriber,upon being rung, removes his receiver from the switchhook, therebydisconnecting. the loud speaker 11 and connecting the telephone set intocircuit with the line L. Upon hanging up the receiver at the endof theconversation, the loud speaker will again be con.- nected into circuitand as soon as the connection is taken down at the central office bywithdrawing the plug P, the cut-0E relay will be deenergized and thecircuit restored to the program transmitting condition.

If, while the line is being used for program receiving, the subscriberdesires to make a call, he may do so by simply remov|- ing the receiverfrom the switchhook, which disconnects the loud speaker 11 from the lineand'at the same time connects the subscribers set into the circuit. Theline relay LR, which is included in the program connection, will beenergized and complete a circuit for the line lamp 15. The operator uponobserving the glowing "of the lamp, will insert the plug P of a cord inthe answering jack, thereby energizing the cutoff relay to disconnectthe line L from the program circuit and to connect it to the an,-swering jack. Restorationof the circuit to the program transmittingcondition at the end of the conversation Wlll. be as previouslydescribed. a

Fig. 2 illustrates .a circuit similar to that shown in Fig. 1. In thisarrangement, however, the substation is equipped witha vacuum tubeamplifier 32 in addition to the loud speaker 11. In order to avoid theinstallation of batteries at the subscribers station, the circuit is soarranged that the 1 current for operating the plate and filamentcircuits of the amplifier is furnishedbver the line from the centraloffice. The plate current may be furnished from a 48-volt battery,'forexample, through the winding of the marginal line relay LR over the ringside of the line. The filament current, on the other hand, may besupplied from a lO-volt battery over the tip side of the line- Since-thetelephone line may act as an antenna and pick up transmission from aradio station, the subscriber might use the amplifier and loud speakerto detect the radio transmission at such times as the central programequipment is not functioning. In order to prevent this, a switch K isprovided at the central ofiice for disabling the current supply circuitof the amplifier, while at the same time providing the usual directcurrent supply-for thetelephone substation equipment.

In the circuit of Fig. 2, as well as in Fig. 1, the line is normallyconnected to the program circuit 28 over the contacts of the cutofi'relay, so that the subscriber, in order to obtain the programtransmission, merely throws the key K at the substation, therebycompleting connection to the input transformer 34 of the amplifier '42and at the same time completing the filament and plate circuits of theamplifier. When the central program equipment is operating, and the lineL is disconnected from the program trunk andconnected to the switchingjack J'- for the purpose of establishing a telephone connection, anetwork N may be connected tothe program trunk. The network N simulatesthe impedance of the line and thereby maintains constant the impedanceof the. network of circuits supplied from the program trunk. If thisarrangement were not provided and a material number of the linessupplied from the same program circuit were simultaneously used fortelephonic purposes, the program transmission to the remaining lineswould be greatly increased.

Further details of the invention may be understood from the descriptionof the operation, which is as follows: When the program service is beingapplied to the line L over the circuit 28 through the transformer 27over the normal contacts of the cut-off relay COR and through thetransformer 27 the switch K will be a'ctuatedto connect the 48-voltbattery to the bus-bar 30 and the lO-volt filament battery to thebus-bar lot Ill)

31. Current supply circuits for the ampli-- fiers of all of the linesconnected to the busbars 30 and 31 will thus be provided. The subscribermay now avail himself of this service by actuating the key K. Thiscloses the filament circuit from the 48-volt battery over the upper makecontact of the'key K bus-bar 30,'through the winding of the line relayLR, over the armature 32 of the cutoff relay COR, over the ringconductor of the line, back contact of the switchhook of the subscribersset 10, left-hand make contact of the key K, and through the retard coilto the plate of the amplifier 42. The

line relay IIR is marginal and is not actuated by the small currentflowing through the high impedance of the plate circuit.

The filament circuit is completed from the 10-volt battery, over thelower make contact of the key K bus-bar 31, armature. 34 of L,right-hand make contact of the key K,-

the cut-off relay COR, tip side of the line through the retard coil tothe filament of the amplifier 42 to ground. The amplifier 'is nowenergized and amplifies the program current transmitted over the line tothe loud speaker 11.

If while the circuit is in this condition the subscriber wishes toinitiate a call, the receiver is removed from the hook, thereby openingthe bridge including the input transformer 34 of the amplifier 42 andalso opening the battery supply circuit for the plate of the amplifier,so that the amplifier and loud speaker cease to function. A lowimpedance path is at the same time closed over the line L through thesubscribers set 10 as follows: from the 48-volt battery, over thebus-bar 30, through the windin of the marginal relay LR, over the riri gsite of the line, over the subscribcrs switehhook, through thesubscribers set 10, back over the tip side of the line L and over thebusbar 31 to the 1(l-volt filament battery. The

whereby the cut-ofi' relay COR is actuated.- The cut-off relay COR, uponattracting its armatures 32 and 34, disconnects the line L from theprogram trunk and connects it to the tip and ring conductors of the jackJ.

; At its armature 35,- the cutofi" relay opens the circuit of the linelamp 15 and at its armature 36 the cut-off relay substitutes the networkor resistance N for the line L, thereby maintaining the impedancelooking through the transformer 27 from the program circuitsubstantially the same as when I has remained aotuated,-the subscriberwill receive the program transmission as before.

If. a call comes in for the line L the operator may, by inserting theplug of the connecting cord into the jack J, energize thecut-ofi' relay,which at once disconnects the line L from the program circuit andconnccts it to the ack J as before. Thevcurrent supply circuit for theamplifier 42 will be opened by the armatures 32. and 34 of the cut-o'fl'relay, so'that the amplifier and loud speaker at the subscribers stationwill be inoperative. Upon the subscriber receiving the ringing signal,he will remove therethereby de-,

ceiver from the switehhook and the telephone conversation may-take placein the usual manner. At the conclusion of the conversation the circuitsmay be restored to the program condition as previously described.

When the program apparatus at the central station is not functioning,the key K will be restored to normal, thereby disconnecting the 48-voltbattery and the lO-volt battery from the ring and tip sides,respectively, of the various lines. The ring. side of the lines Will beconnected over the normal contactof the key K, to the usual 24- voltbattery and the tip sides of the lines will be grounded over the normalcontact of the key K Under this condition the line relay LR will respondto the operation of the switehhook in the usual manner, so thattelephone connections may take place. lhe amplifier 42, associated withthe loud speaker set, will be rendered inoperative, however, and thuseffectually prevent the siibscriber from using the amplifier and loudspeaker to receive radio transmission which might be picked up by theline L acting as an antenna.

It will be-obvious that the general principles herein disclosed may beembodied in other and different organizations widely different fromthose illustrated without departin from the spirit and scope'ot theappen ed claims.

'What is claimed is: v

1. In a telephone system, a telephone line terminating at a centraloflice at one end and a subscribers station at the other, a telellll)phone set at the subscribers station, nor

used in conjunction with the establishment of such interconnections,connections normally associated with the line leading to a programtransmitting station,'said line re.- lay being included in said lastmentioned connections and being unactuated during the transmission ofprogram currents to the subscriber, and means for closing said normallyopen conductors.

2.. In a telephone systenr, a telephone line terminating at a centraloflice at one end and a subscribers station at the other, a telephoneset at the subscribers station, normally open conductors at the centralof fice leading to switching means for interconnecting. said line withother linesfor ordinary telephonic intercommunication, a line relay usedin conjunction with the establishment of such interconnections,connections normally associated with the line leading to a programtransmitting station, said. line relay being included in said lastmentioned connections and being unactuated during the transmission ofprogram I currents to the subscriber, and means for opening theconnections to the program station and closing said normally openconductors when said line is used for ordinary telephone purposes.

3. In a telephone system, a telephone line terminating at a centraloffice at one end and a subscribers station at the other, a jack at thecentral otfice forintereonnecting said line with other telephone linesfor telephonic intercommunication, connections from said line to saidjack, said connections being normally disconnected from the line,connections normally associated with the line extending to a programtransmitting station, a line relay included in said last mentionedconnections, said line relay being unactuated during the transmission ofprogram currents to the subscriber, and a line lamp controlled by saidline relay for indicating that the subscriber is calling for theestablishment of an ordinary telephone connection.

4. In a telephone terminating at a central oflice at one end and asnbscribers station at the other, a jack at the central oflice forinterconnecting said line with other telephone lines for telephonicintercommunication, connections from said line to said jack, saidconnections being normally disconnected from the line,

connections normally associated with the line extending to a programtransmitting station, a line relay included in said last mentionedconnections, said line relay being 7 unactuated during the transmissionof program currents to the subscriber, a line lamp controlled by saidline relay for indicating that the subscriber is calling for theestablishment of an ordinary telephone connection, and means operatingto disconnect the line relay and program-connections from the line whenit is used for ordinary telephone purposes.

5. In a telephone system, a telephone line terminating at a centraloflice at one end and a subscribers station at the other, a jack at thecentral ofiice for interconnecting said line with other telephone linesfor telephonic intercommunication, connections from said line to saidjack, said connections being normally disconnected from the line,connections normally associated with the line extending to a programtransmitting station, mentioned connections, said line relay beingunactuated during the transmission of proram currents to the subscriber,a line amp controlled b said line relay for indicating that the suscriber is calling for the establishment of an ordinary telephoneconnection, a cut-off relay, said cut-ofi relay being actuated when'aplug is inserted in the ack in establishing either incoming or I acentral ofiice, switching means at said system, a telephone 11119bus-bars, each set of bus-bars beingcoma line relay included in saidlast impedance characteristics, and each of the lines of the grouphaving connections whereby it may be associated with said busbars, andan amplifier for transmitting the program currents to said bus-bars withthe amplitude required for proper transmission over said group of lines.

7. In a telephone system, a plurality of telephone lines terminating atone end in central ofiice whereby any one of said lines may be connectedwith another line for ordinary telephonic intercommunication, aplurality of program transmitting stations adapted to be connected tocorresponding mon to a group of telephone lines and the telephone linesof each roup having similar impedance characteristics, and amplifyingmeans for amplifying the currents transmitted from each program stationto a group of telephone lines.

8. In a telephone, system, a plurality of telephone lines terminating atone end in a central ofiice, switching means at said central oflicewhereby any one of said lines may be connectedwith another line forordinary telephonic intercommunication, a plurality of programtransmitting stations adapted to be connected to corresponding bus-bars,each set of bus-bars being common to a group of telephone lines, thetelephone lines of each group havin similar impedancecharacteristics,amplii% ing means for amplifying the currentstransmitted from eachprogram station to a group of telephone lines, andmeans for interchanging the connections between programv stations anddifferent groups of telephone lines so that any group may be connectedto any desired program station. p

9. In a telephone system, a plurality of telephone lines terminating atone end in a central ofiice, switching means at said cenany one ofsaidlines may another line for ordinary tral oifice whereby be connected wit telephonic intercommunication, a plurality group of telephone lines,the telephone lines.

fice leading to switching means for interconnecting said line with otherlines forordinary telephonic intercommunication, a line relay used incon unct1on with the establishment of such interconnections, connectionsnormally associatedwith the line leading to a program transmittingstation,

said line relay being included in said last mentioned connections andbeing unactuated during the transmission of program currents to thesubscriber, means for disconnecting the connei'tions to the'programstation and closing said normally open con x ductors when said line isused for ordinary I telephone purposes, and means for reestablishing theconnection to the program station at the end of the ordinary telephoneconversation.

a subscribers station at the other, a jack at the central office forinterconnecting said line with other telephone lines for telephonicintercommunication, connections from said line to said jack, saidconnections being normally disconnected from the line, connectionsnormally associated with the line extending to a program transmittingstation, a line relay included in said last mentioned connections, saidline relay being unactuated during the transmission of program currentsto the subscriber, a line lamp controlled by said line relay forindicating that the subscriber is calling for the establish ment of anordinary telephone connection, and means to give a busy indication atsaid jackwhen the program connection is completed.

In testimonywhereof, I have signed my name to this specification this10th day of November, 1922.

JOHN F. TOOMEY.

